Fluid conveyance safety devices, methods, and systems

ABSTRACT

The disclosed subject matter includes a structure and method for making a dual-lumen needle from single lumen needles to take advantage of the much higher economies of scale. Variations include two needles joined by a flow junction and one needle and a single cannula joined by a flow junction. In addition disclosed are methods of using a dual-lumen needle in a two needle access for blood treatment is disclosed in which at least venous flow is provided through a dual-lumen needle with arterial flow just sufficient to provide air infiltration detection in the event of withdrawal of the dual-lumen needle.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 61/406,947 filed Oct. 26, 2010, which is herebyincorporated by reference as if set forth herein in its entirety.

FIELD

The disclosed subject matter relates to the detection of leaks, forexample, leaks resulting from a loss of integrity of a blood circuit.

BACKGROUND

Many medical procedures involve the extraction and replacement offlowing blood from, and back into, a donor or patient. The reasons fordoing this vary, but generally, they involve subjecting the blood tosome process that cannot be carried out inside the body. When the bloodis outside the patient it is conducted through machinery that processesthe blood. The various processes include, but are not limited to,hemodialysis, hemofiltration, hemodiafiltration, blood and bloodcomponent collection, plasmapheresis, aphresis, and blood oxygenation.

One technique for extracorporeal blood processing employs a single“access,” for example a single needle in the vein of the patient or afistula. A volume of blood is cyclically drawn through the access at onetime, processed, and then returned through the same access at anothertime. Single access systems are uncommon because they limit the rate ofprocessing to half the capacity permitted by the access. As a result,two-access systems, in which blood is drawn from a first access, calledan arterial access, and returned through a second access, called avenous access, are much faster and more common. These accesses includecatheters, catheters with subcutaneous ports, fistulas, and grafts.

The processes listed above, and others, often involve the movement oflarge amounts of blood at a very high rate. For example, 500 ml. ofblood may be drawn out and replaced every minute, which is about 5% ofthe patient's entire supply. If a leak occurs in such a system, thepatient could be drained of enough blood in a few minutes to cause lossof consciousness with death following soon thereafter. As a result, suchextracorporeal blood circuits are normally used in very safeenvironments, such as hospitals and treatment centers, and attended byhighly trained technicians and doctors nearby. Even with closesupervision, a number of deaths occur in the United States every yeardue to undue blood loss from leaks.

Leaks present a very real risk. Leaks can occur for various reasons,among them: extraction of a needle, disconnection of a luer, poormanufacture of components, cuts in tubing, and leaks in a catheter.However, in terms of current technology, the most reliable solution tothis risk, that of direct and constant trained supervision in a safeenvironment, has an enormous negative impact on the lifestyles ofpatients who require frequent treatment and on labor requirements of theinstitutions performing such therapies. Thus, there is a perennial needin the art for ultra-safe systems that can be used in a non-clinicalsetting and/or without the need for highly trained and expensive staff.Currently, there is great interest in ways of providing systems forpatients to use at home. One of the risks for such systems is the dangerof leaks. As a result, a number of companies have dedicated resources tothe solution of the problem of leak detection.

The first level of protection against return line blood loss is the useof locking luers on all connections, as described in InternationalStandard ISO 594-2 which help to minimize the possibility of spontaneousdisconnection during treatment. Care in the connection and taping oflines to the patient's bodies is also a known strategy for minimizingthis risk.

A higher level of protection is the provision of venous pressuremonitoring, which detects a precipitous decrease in the venous linepressure. This technique is outlined in International Standard IEC60601-2-16. This approach, although providing some additionalprotection, is not very robust, because most of the pressure loss in thevenous line is in the needle used to access the patient. There is verylittle pressure change in the venous return line that can be detected inthe event of a disconnection, so long as the needle remains attached tothe return line. Thus, the pressure signal is very weak. The signal isno stronger for small leaks in the return line, where the pressurechanges are too small to be detected with any reliability. One way tocompensate for the low pressure signal is to make the system moresensitive, as described in U.S. Pat. No. 6,221,040, but this strategycan cause many false positives. It is inevitable that the sensitivity ofthe system will have to be traded against the burden of monitoring falsealarms. Inevitably this leads to compromises in safety. In addition,pressure sensing methods cannot be used at all for detecting smallleaks.

Yet another device for checking for leaks in return lines is describedin U.S. Pat. No. 6,090,048. In the disclosed system, a pressure signalis sensed at the access and used to infer its integrity. The pressurewave may be the patient's pulse or it may be artificially generated bythe pump. This approach cannot detect small leaks and is not verysensitive unless powerful pressure waves are used, in which case theeffect can produce considerable discomfort in the patient.

Currently, with lower staffing levels comes the increased risk ofunattended leaks. Thus, there has been, and continues to be, a need inthe prior art for a foolproof approach to detection of a return lineleak or disconnection.

In single-access systems, loss of blood through the patient access andblood circuit can be indirectly detected by detecting the infiltrationof air during the draw cycle. Air is typically detected using anultrasonic air detector on the tubing line, which detects air bubbles inthe blood. The detection of air bubbles triggers the system to halt thepump and clamp the line to prevent air bubbles from being injected intothe patient. Examples of such systems are described in U.S. Pat. Nos.3,985,134, 4,614,590, and 5,120,303.

One type of double access is provided by a two-lumen needle or catheter,such as described in U.S. Pat. Nos. 4,202,332 and 4,144,884. These use asingle access point, for example a fistula. Blood is returned and drawnthrough a coaxial pair of channels at the end of the catheter or needle.

An example of a system that uses a dual-lumen needle for leak detectionis described in US 20040186415. This publication describes a leak safeaccess needle and blood circuit combined in a fluid circuit with theaccess needle configured as a double lumen access needle whose venousline is permanently attached to the fluid circuit. The arterial line hasan air detection device. In this configuration, the only way the venousline can be disconnected is for the access needle to be withdrawn fromthe patient, which will necessarily result in disconnection of thearterial line, which in turn will be detected by air infiltration intothe arterial line. While dual-lumen needles are effective for detectingleaks, they are expensive, suffer from a recirculation problem, and tendto be limited in terms of the volume rate of blood they can handle.

SUMMARY

According to embodiments of the disclosed subject matter, a method ofmanufacturing a dual-lumen needle, includes providing a first singlelumen needle with a first metal cannula and a first plastic hub thatsupports the first metal cannula; providing a junction part of plastichaving three cylindrical openings, first and second of the openingsbeing coaxial and a third opening having an axis that crosses the commonaxis of the first two openings. The method further includes providing asecond metal cannula whose internal diameter is larger than an innerdiameter of the first metal cannula. The first opening has an internaldiameter approximately the same as an outer diameter of the secondcannula. The second opening is sized and shaped to receive the firstplastic hub. The method further includes inserting the second cannula inthe first opening and inserting the first plastic hub in the secondopening including the first metal cannula with the common axis of thefirst and second openings. The inserting operations are performedincluding aligning the first and second metal cannulas coaxially. Thejunction part is configured such that the two inserting operations formsa fluid flow channel joining the third opening for fluid communicationwith an annular space coaxial with and lying between the first andsecond metal cannulas that is isolated from the second port.

The inserting the second cannula may be performed before the insertingthe first plastic hub. The inserting the second cannula may be performedafter the inserting the first plastic hub. The providing a second metalcannula may include providing the second metal cannula supported by asecond plastic hub, the combination of the second metal cannula and thesecond plastic hub defining a needle with a port configured forattachment to a fluid line, wherein the inserting of the second cannulaincludes inserting the second plastic hub supporting the second cannulain the first opening. The method may include solvent bonding the hub tothe second opening. The hubs may have opposing wings configured forhandling and taping.

According to embodiments of the disclosed subject matter, a double lumenneedle has a first needle set having a resin winged hub and a firstmetal cannula. The first needle set winged hub has a first hub port. Asecond needle set has a resin winged hub and a second metal cannula. Thesecond needle set winged hub has a second hub port. The first needle setcannula is larger than the second. The first and second needle setwinged hubs having first and second cylindrical portions, the firstextending along a base of the respective cannula and the secondextending away from the respective cannula and forming an openingadapted for receiving a tube. A junction part has first and secondrecessed ports sized and shaped to receive the first and secondcylindrical portions. The first needle set second cylindrical portion isinserted in the junction part first recessed port and the second needleset first cylindrical portion being inserted in the junction part secondrecessed port such that the second metal cannula extends into the firstmetal cannula. The junction part has a third recessed port in fluidcommunication a channel that includes an annular spaced between thefirst and second metal cannulas. The channel is fluidly isolated fromthe lumen of the second metal cannula. The junction part is configuredthat the second hub port is available for direct connection to a tube toform a channel with the lumen of the second metal cannula and the thirdrecessed port is available for connection to another tube.

According to embodiments of the disclosed subject matter, a method ofusing first and second single lumen needles, each having a resin hub anda metal cannula, the each hub having port opposite the metal cannula.The method includes inserting the first needle cannula in a first portof a T-junction conduit and the second needle hub port in a second portof the T-junction conduit opposite the first port such that the firstneedle cannula extends through the T-junction conduit into the secondneedle cannula; bonding the first and second needle hubs to theT-junction conduit; attaching respective tubing portions to the firstneedle hub and a third port of the T-junction.

According to embodiments of the disclosed subject matter, a method ofmanufacturing a dual-lumen needle, includes providing a first singlelumen needle with a first cannula and a first plastic hub that supportsthe first cannula; providing a junction part of plastic having threecylindrical openings, first and second of the openings being coaxial anda third opening having an axis that crosses the common axis of the firsttwo openings. The method further includes providing a second cannulawhose internal diameter is larger than an inner diameter of the firstcannula. The first opening has an internal diameter approximately thesame as an outer diameter of the second cannula. The second opening issized and shaped to receive the first plastic hub. The method furtherincludes inserting the second cannula in the first opening and insertingthe first plastic hub in the second opening including the first cannulawith the common axis of the first and second openings. The insertingoperations are performed including aligning the first and secondcannulas coaxially. The junction part is configured such that the twoinserting operations forms a fluid flow channel joining the thirdopening for fluid communication with an annular space coaxial with andlying between the first and second cannulas that is isolated from thesecond port.

The inserting the second cannula may be performed before the insertingthe first plastic hub. The inserting the second cannula may be performedafter the inserting the first plastic hub. The providing a secondcannula may include providing the second cannula supported by a secondplastic hub, the combination of the second cannula and the secondplastic hub defining a needle with a port configured for attachment to afluid line, wherein the inserting of the second cannula includesinserting the second plastic hub supporting the second cannula in thefirst opening. The method may include solvent bonding the hub to thesecond opening. The hubs may have opposing wings configured for handlingand taping.

According to embodiments of the disclosed subject matter, a double lumenneedle has a first needle set having a resin winged hub and a firstcannula. The first needle set winged hub has a first hub port. A secondneedle set has a resin winged hub and a second cannula. The secondneedle set winged hub has a second hub port. The first needle setcannula is larger than the second. The first and second needle setwinged hubs having first and second cylindrical portions, the firstextending along a base of the respective cannula and the secondextending away from the respective cannula and forming an openingadapted for receiving a tube. A junction part has first and secondrecessed ports sized and shaped to receive the first and secondcylindrical portions. The first needle set second cylindrical portion isinserted in the junction part first recessed port and the second needleset first cylindrical portion being inserted in the junction part secondrecessed port such that the second cannula extends into the firstcannula. The junction part has a third recessed port in fluidcommunication a channel that includes an annular spaced between thefirst and second cannulas. The channel is fluidly isolated from thelumen of the second cannula. The junction part is configured that thesecond hub port is available for direct connection to a tube to form achannel with the lumen of the second cannula and the third recessed portis available for connection to another tube.

According to embodiments, the disclosed subject matter includes a methodof using first and second single lumen needles, each having a resin huband a cannula, the each hub having port opposite the cannula. The methodincludes inserting the first needle cannula in a first port of aT-junction conduit and the second needle hub port in a second port ofthe T-junction conduit opposite the first port such that the firstneedle cannula extends through the T-junction conduit into the secondneedle cannula; bonding the first and second needle hubs to theT-junction conduit; attaching respective tubing portions to the firstneedle hub and a third port of the T-junction.

According to embodiments of the disclosed subject matter includes adual-lumen needle with an inner cannula having an inner lumen and anouter cannula having an inner lumen. A hub has first and second ports,the hub being configured to support the inner and outer cannulas withthe outer cannula in coaxial relation to the inner cannula therebydefining an annular channel between the inner and outer cannulas. Thehub is further configured to define a first fluid channel connecting thefirst port with the inner cannula inner lumen and second fluid channelconnecting the annular space to the second port. The inner and outercannulas are blunt tip needles adapted for use with buttonhole-typevascular accesses and the inner cannula extends through and beyond theouter cannula at a distal end thereof extending away from the hub.

The hub may be a rigid structure such that the inner and outer cannulasare held in fixed relation to each other. The inner and outer cannulasmay be metal and the hub of resin. The hub may have a T shape with oneof the first and second ports on the crossbar opposite the inner andouter cannulas and the other of the first and second ports on the stem.The hub may have a Y shape.

According to embodiments, the disclosed subject matter includes a methodof using the above needle comprising inserting the inner and outercannulas through a buttonhole vascular access.

According to embodiments, the disclosed subject matter includes, adual-lumen needle with an inner cannula having an inner lumen, an outercannula having an inner lumen, and a hub having first and second ports.The hub is configured to support the inner and outer cannulas with theouter cannula in coaxial relation to the inner cannula thereby definingan annular channel between the inner and outer cannulas. The hub isfurther configured to define a first fluid channel connecting the firstport with the inner cannula inner lumen and second fluid channelconnecting the annular space to the second port. The outer cannula ismovable between an extended position where a distal tip of the innercannula extends well beyond that of the outer cannula and a retractedposition in which the outer cannula is closer to the hub. The hub isconfigured with a flexible channel portion and the outer cannula isaffixed to the flexible channel portion of the hub to permit themovement of the outer cannula without sliding engagement of the outercannula with the hub.

The hub may be of plastic. The flexible channel portion may define acylindrical channel portion. The flexible channel portion may bedeformable with two stable conformations, each corresponding to arespective one of the extended and retracted positions of the outercannula, whereby the outer cannula snaps from the extended to theretracted position. The hub may include a flange portion extendingradially from a point where the outer cannula meets the hub tofacilitate moving the outer cannula from the extended position to theretracted position.

According to embodiments, the disclosed subject matter includes a methodof using the needle with at least one movable cannula according to theabove embodiments, including cannulating a patient with the outercannula in the extended position, moving the outer cannula to theretracted position after cannulating the patient, and simultaneouslyinfusing and withdrawing blood through the first and second ports,respectively.

According to embodiments, the disclosed subject matter includes a methodincluding withdrawing blood from a patient through a first cannula,infusing blood into a patient through a second cannula, withdrawingblood through a secondary channel affixed to the second cannula suchthat a withdrawal of the second cannula from the patient is necessarilyattended by a disruption of fluid communication through the loss ofpatency and generating an alarm signal responsively to air being drawninto the secondary channel.

According to embodiments, the disclosed subject matter includes a methodof detecting a defective fluid connection including pumping fluidthrough a fluid circuit having incoming connector under negativepressure and an outgoing connector under positive pressure so the fluidcirculates between the incoming and outgoing connectors through thefluid circuit, withdrawing the fluid through the outgoing connector insuch a way that a disconnection of the outgoing connector causesinspiration of air into the fluid circuit, and detecting the inspirationof air into the fluid circuit responsively to a disconnection of theoutgoing connector and generating a signal responsively thereto.

According to embodiments, the disclosed subject matter includes avascular access device with a blood circuit having an arterial bloodline and a venous blood line. The venous blood line is connected to afirst access needle and the arterial blood line being connected to asecond access needle. The venous blood line is connected to an accesscomponent affixed to the second access needle and configured such thatwhen the second access needle is used to infuse blood into a patient,the access component is positioned to withdraw blood and convey it intothe venous line.

The second access needle may be a dual-lumen needle and the accesscomponent is a lumen of the dual-lumen needle.

According to embodiments, the disclosed subject matter includes avascular access device with a blood circuit having an arterial bloodline and a venous blood line. The venous blood line is connected to afirst access needle and the arterial blood line is connected to a secondaccess needle. The venous blood line is connected to an access componentaffixed to the second access needle and configured such that when thesecond access needle is used to infuse blood into a patient. The accesscomponent is positioned to withdraw blood and convey it to an airdetector.

According to embodiments, the disclosed subject matter includes methodof making a dual-lumen needle, comprising: providing a first singlelumen needle with a first cannula and hub that supports the firstcannula; providing a junction part of having three cylindrical openings,first and second of the openings being coaxial and a third openinghaving an axis that crosses the common axis of the first two openings;providing a second cannula whose internal diameter is larger than aninner diameter of the first cannula; the first opening having aninternal diameter approximately the same as an outer diameter of thesecond cannula; the second opening being sized and shaped to receive thefirst hub; and inserting the second cannula in the first opening;inserting the first hub in the second opening including the firstcannula with the common axis of the first and second openings; theinserting operations being performed including aligning the first andsecond cannulas coaxially and forming a seal that defines a channelbetween the third opening and an annular space between the first andsecond cannulas; the junction part being configured such that the twoinserting operations forms a fluid flow channel joining the thirdopening for fluid communication with an annular space coaxial with andlying between the first and second cannulas that is isolated from thesecond port. The inserting of the second cannula may be performed beforethe inserting the first hub. The inserting of the second cannula may beperformed after the inserting the first hub. The forming a seal mayinclude applying epoxy in a position that forms a part of an interiorsurface of the flow channel. The providing a second cannula may includeproviding the second cannula supported by a second hub, the combinationof the second cannula and the second hub defining a needle with a portconfigured for attachment to a fluid line, wherein the inserting of thesecond cannula includes inserting the second hub supporting the secondcannula in the first opening. The method may further include solventbonding the hub to the second opening.

According to embodiments, the disclosed subject matter includes adual-lumen needle, comprising: an inner cannula having an inner lumen;and an outer cannula having an inner lumen; a hub having first andsecond ports. The hub may be configured to support the inner and outercannulas with the outer cannula in coaxial relation to the inner cannulathereby defining an annular channel between the inner and outer cannulasand the hub may be further configured to define a first fluid channelconnecting the first port with the inner cannula inner lumen and secondfluid channel connecting the annular space to the second port. The innercannula may be movable between an extended position where a distal tipof the inner cannula extends well beyond that of the outer cannula and aretracted position in which the inner cannula tip is closer to the hub.The hub may be configured with a flexible wall portion remote from thesecond fluid channel and the inner cannula is affixed to the flexiblewall portion of the hub to permit the movement of the inner cannula.

The hub may be of plastic. The flexible wall portion may define anaccordion wall shape. The method may further include cannulating apatient with the outer cannula in the extended position, moving theinner cannula to the extended position after cannulating the patient,and simultaneously infusing and withdrawing blood through the first andsecond ports, respectively.

According to embodiments, the disclosed subject matter includes adual-lumen needle, comprising: an inner cannula surrounded by an outercannula both cannulas having sharp tips, there being a gap between theinner and outer cannulas, thereby defining an annular flow channel; theinner cannula extending beyond the outer cannula; a bridging cutterextending between the inner and outer cannulas and positioned such thata cut is made that prevents a separate cut being made in the skin of apatient when the outer cannula enters reaches the skin of a patient asthe needle is progressively inserted during cannulation.

The bridging cutter may be aligned radially and parallel with respect toa common access of the inner and outer cannulas. The bridging cutter maybe aligned radially and parallel with respect to a common access of theinner and outer cannulas and wherein a cutting edge of the cutterextends diagonally from a cutting edge of the inner cannula to a cuttingedge of the outer cannula.

According to embodiments, the disclosed subject matter includes a needleset for a two needle vascular access, comprising: a dual-lumen needlewith arterial and venous ports; a single lumen needle with an arterialport; and an arterial line with an arterial connector connected to thesingle lumen needle arterial port and the dual-lumen needle arterialport; a venous line with a venous connector connected to the venousport.

According to embodiments, the disclosed subject matter includes a needleset for a two needle vascular access, comprising: a first dual-lumenneedle with arterial and venous ports; a second dual-lumen needle witharterial and venous ports; an arterial line with an arterial connectorconnected to the first and second dual-lumen needle arterial ports; anda venous line with an venous connector connected to the first and seconddual-lumen needle venous ports.

The cannulas may have blunt tips suitable for buttonhole access. Thedual-lumen needles may have an inner cannula extending beyond the outercannula. The arterial port(s) may be connected to an annular spacedbetween inner and outer cannulas of the dual-lumen needle(s).

According to embodiments, the disclosed subject matter includes adual-lumen needle, comprising: an inner cannula surrounded by an outercannula both cannulas having sharp tips, there being a gap between theinner and outer cannulas, thereby defining an annular flow channel; theinner cannula extending beyond the outer cannula; the outer cannulahaving a cutting edge at a tip thereof that forms an approximatelyelliptical contour that lies approximately in a plane forming a diagonalwith axis of the outer cannula such that the outer cannula cutting edgehas distal-most and proximal-most portions; the inner cannula axis beingpositioned eccentric of the outer cannula axis such that the innercannula all is positioned directly adjacent the outer cannula cuttingedge distal-most portion.

A resilient spacer may be provided and configured to urge the innercannula toward the inner wall of the outer cannula.

Objects and advantages of embodiments of the disclosed subject matterwill become apparent from the following description when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will hereinafter be described in detail below with referenceto the accompanying drawings, wherein like reference numerals representlike elements. The accompanying drawings have not necessarily been drawnto scale. Where applicable, some features may not be illustrated toassist in the description of underlying features.

FIGS. 1A and 1B each show a respective single lumen butterfly needle,one selected with a long narrow diameter cannula and the other with ashort large diameter cannula according to embodiments of the disclosedsubject matter.

FIG. 1C shows a junction unit allowing the needles of FIGS. 1A and 1B tobe combined to form a single dual-lumen needle according to embodimentsof the disclosed subject matter.

FIG. 1D shows a cross-section of a dual-lumen needle resulting from thecombination of components of FIGS. 1A through 1C according toembodiments of the disclosed subject matter.

FIG. 2 is a perspective view of the dual-lumen needle similar to that ofFIG. 1D.

FIG. 3A shows a side section view of a buttonhole needle which may beused for an outer cannula of a dual-lumen needle according toembodiments of the disclosed subject matter.

FIG. 3B shows a side view of the end of the buttonhole needle which maybe used for an outer cannula of a dual-lumen needle according toembodiments of the disclosed subject matter.

FIG. 3C shows an end view of the buttonhole needle which may be used foran outer cannula of a dual-lumen needle according to embodiments of thedisclosed subject matter.

FIG. 4 shows a dual-lumen needle with alternative features according toembodiments of the disclosed subject matter.

FIG. 5 shows a dual-lumen needle set with venous and arterial linesaccording to embodiments of the disclosed subject matter.

FIG. 6 shows a process for assembling a dual-lumen needle according toembodiments of the disclosed subject matter.

FIG. 7A shows a method and system for using a dual-lumen needle in ablood processing treatment according to embodiments of the disclosedsubject matter.

FIG. 7B shows an alternative method and system for using two dual-lumenneedles in a blood processing treatment according to embodiments of thedisclosed subject matter.

FIG. 7C shows an alternative method and system for using a dual-lumenneedle in a blood processing treatment according to embodiments of thedisclosed subject matter.

FIG. 7D shows a needle set with a main arterial line and a main arterialline having a secondary arterial branch connected to the main arterialline according to embodiments of the disclosed subject matter.

FIG. 8 shows a dual-lumen needle having another structure according toembodiments of the disclosed subject matter.

FIGS. 9A through 9D show features that may be used with dual-lumenneedles according to embodiments of the disclosed subject matter.

FIGS. 10A and 10B show a dual-lumen needle with an inner cannula thatcan be retracted and extended according to embodiments of the disclosedsubject matter.

FIGS. 11A and 11B show a dual-lumen needle with an outer cannula thatcan be retracted and extended according to embodiments of the disclosedsubject matter.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a single lumen “butterfly” needle 100 with a long narrowdiameter cannula 124 held by a hub 110. The hub 110 has wings 116 oneither side to allow the needle 100 to be manipulated more easily, serveas an orienting reference, and allow the needle to be taped down to skinof a patient after cannulation. In embodiments, the needle 100 is whatis known as a blunt needle having a fully radius edge at its tip 128 andgenerally used to access so-called buttonhole type sites. The hub 110may allow the attachment of a flexible tube (not shown) by means of aninternal recess 122 or by inserting the hub 110 into a tube. The cannula124 may be of metal or other material and may be frictionally engagedwith the hub 110, attached by means of fasteners or adhesives or weldedto the hub 110 as permitted by the selection of materials.

FIG. 1B shows a single lumen “butterfly” needle 102 with a cannula 126whose diameter is wider than cannula 124 of FIG. 1A. The cannula 126 isheld by a hub 112. The hub 112 has wings 116 on either side. Inembodiments, the needle 102 is also a blunt needle having a fully radiusedge at its tip 130. The hub 112 may also allow the attachment of aflexible tube by with an internal recess 122 or by inserting the hubinto a tube. The cannula 126 may also be of metal or other material andmay be frictionally engaged with the hub 112, attached by means offasteners or adhesives or welded to the hub 112 as permitted by theselection of materials.

FIG. 10 shows a junction component 104 into which the needle 100 and 102hubs 110 and 112 can be inserted to be assembled to form a singledual-lumen needle as shown in FIG. 1D. The junction component 104 has arecess 132 for receiving a heel end 123 of hub 112 of needle 102 and arecess 134 for receiving a top end 113 of hub 110 of needle 100. Abranching channel 138 is formed within the junction component 104 thatconnects the recess 136. To the lumen of cannula 126 as shown in theassembled dual-lumen needle 102 of FIG. 1D.

FIG. 1D shows a cross-section of a dual-lumen needle which may beassembled using the process of FIG. 6. Needles of suitable respectivesizes 100 and 102 are selected at S10, for example from a vendorcatalog. These may be purchased as fully functioning and ready to use orsubassemblies from a manufacturer. The needles hubs and cannulas ofneedles 100 and 102 are pre-assembled, for example, with epoxy.

For example, needle 100 may carry an 18 ga. cannula with an outerdiameter of 1.27 mm, a length of 40 mm, and a wall thickness of 0.09 mm.The needle 100 may be a blunt needle. The cannula 124 may or may nothave a back eye to promote circulation of blood. The cannula of theneedle 100 may also be a sharp cannula instead of a blunt one. Needle102 may carry a 14 ga. cannula with an outer diameter of 2.11 mm, alength of 24 mm, and a wall thickness of 0.11 mm. The cannula 126 may bea blunt needle. The cannula 126 may or may not have a back eye topromote circulation of blood. The cannula 126 of the needle 102 may alsobe a sharp cannula instead of a blunt one.

The wings 116 may optionally be trimmed as indicated at S12. Forexample, the wings 116 of hub 110 or those of hub 112 may be removed orcut off if desired, leaving wings of the other hub intact and accessiblefor use in cannulation. As indicated at S14, the heel end 123 of hub 112of needle 102 is inserted in the recess 132 of junction component 104with, if required, an adhesive material such as epoxy. At S16, the topend 113 of hub 110 of needle 100 is inserted in recess 134 whileinserting the cannula 124 through opening 135 and into the cannula 126.At step S18, the hub 110 top end 113 may be attached with, if required,an adhesive material such as epoxy. Solvent welding, thermal welding,interference or friction fits may be used to connect the hubs 110 and112 to the junction component 104 as well. The opening 135 permits thecannula 124 to be inserted and the opening 125 may be sealed by thebonding of the hub 110 with the junction component 104. Alternatively, atight fitting opening 135 may form a seal around the cannula 124. Othermechanisms for sealing opening 135 may be used, such as frictionwelding, a separate gasket, or other devices. In any case, the sealingof opening 135 forms a right-angle channel 138 that connects an annulargap 140 between the cannula 124 and 126 with the port defined by recess136. In use, this channel may be used for arterial flow of blood (i.e.,blood is pumped out of the vascular access through the annular gap 140).The lumen of cannula 124 is directly connected to the port defined byrecess 122.

The completed dual-lumen needle is shown in FIG. 1D at 106 and in FIG. 2in a perspective view. Tubes 240 and 242 may be attached to the ports122 and 136, respectively, to form a dual-lumen needle set 240 asillustrated in FIG. 5. The tubes 240 and 242 may carry sealed connectors256 and clamps 250. A standard cap (not shown but configured to seal theneedle 102 and which still may be used since the configuration of thetop of the hub 112 remains unchanged and accessible) may be used to sealthe dual-lumen needle 225 and the set 240 sterilized as a unit andpackaged.

FIG. 3A shows a side section view of a buttonhole needle cannula whichmay be used for an outer cannula or inner cannula of any of thedual-lumen needle embodiments described herein. Needle 200 has a blunttip 204 with a full radius as illustrated. A back eye 208 may beprovided to promote blood flow. The opening end may have a heel curl 202or full radii to prevent unwanted cutting of tissue. In any of thedisclosed embodiments, the outer cannula (e.g., 126 in FIG. 1D) may havea blunt cannula and inner cannula (124 in FIG. 1D) may be a sharpcannula. In such an embodiment, the inner cannula may cut an opening andthe outer cannula may stretch the opening to accommodate it. FIG. 3Bshows a side view of the end of the buttonhole needle cannula. FIG. 3Cshows an end view of the buttonhole needle cannula.

FIG. 4 shows a dual-lumen needle with alternative features. As in theforegoing embodiments, an inner cannula 220 is surrounded by an outercannula 218, with the cannulas being original parts of needles withrespective hubs 215 and 216 which are joined by a junction part 214. Thejunction part 214 has a Y-shape as compared to the T-shape of thedual-lumen needle 106. The lumen of a diagonal branch 208 is incommunication with an annular space between the cannulas 218 and 220.Two pairs of wings 212 stem from the respective hubs 215 and 216. Tubes204 and 206 are fitted to the outside of the hub 215 and the branch 208.

In the foregoing embodiments, two single-lumen needles, each including ahub and a cannula, are connected to form a dual-lumen needle. Inembodiments, the dual-lumen needle has concentric cannulas. At least oneport may be provided by a junction component. In embodiments, one of theports is at the base of the needle forming the inner cannula and oneextends from the junction component. By utilizing existing subassembliesincluding at least the hub and cannula of existing needles, a dual-lumenneedle may be fabricated from components which benefit from the vastproduction economies of scale available for the production of singlelumen needles that are in very wide use. The end product of a dual-lumenneedle takes advantage of the precise manufactured features of theneedle subassemblies such as the alignment of the cannulas to theirrespective hubs and the bonding of the cannula to the hub. The wings ofthe hubs are accessible in the completed dual-lumen needle for use inthe dual-lumen device. In addition, two sets of wings may be provided inthe end product which may provide advantages such as easier gripping,stronger tape-down or other benefits.

FIG. 7A shows a method and system for using a dual-lumen needle in ablood processing treatment. In the embodiments illustrated, thedual-lumen needle described above may be used or any other type ofdual-lumen needle may be used. For example, dual-lumen needles aredescribed in U.S. Pat. No. 4,134,402 or any other suitable device thatensures that withdrawal of the venous connection (the connection thatpumps blood back into the patient's body) is always attended by thedisconnection of the arterial line. The needle should be configured suchthat air will be drawn into the arterial line through the disconnectedvenous line. Thus, if a recirculation flow could be established by awithdrawn needle, then the configuration of the dual-lumen needle wouldnot be suitable. So for example, in the design of the foregoingembodiments, the inner cannula may be used for returning blood to thepatient and the annular space between the cannulas for drawing bloodout. Upon withdrawal of the needle a short-circuit flow would be nearlyimpossible to establish between the annular entry and the tip of theinner cannula and air would surely be drawn in. Alternativeconfigurations are also possible, for example, if the return channel isthe annular channel and the withdrawal is through the inner cannula,recirculating flow may be difficult to establish as well.

In the configuration and method shown in FIG. 7A, a needle set 301 shownin FIG. 7D is used. The needle set 301 has a pair of needles, one 320, aconventional single lumen needle 320, for example buttonhole or sharp,is attached to a main arterial line 318. The needle 320 may have, forexample, a 15 ga. cannula. Another needle, a dual-lumen needle 322 isattached to a main venous line 316 via one of the needle's 322 lumens(here shown as the lumen of the inner cannula). The other lumen ofneedle 322 is attached to a secondary arterial branch 314 connected tothe common arterial line 303, which is also connected to the mainarterial line 318 by a Y junction 319. The needles 320 and 322 may beused in a two-needle access arrangement to be described shortly. Theneedle set 301 may be packaged in a sterile bag 331 or other packagingalong with instructions for using the needle set according to a methodas described presently with reference to FIG. 7A.

For coaxial type dual-lumen needles 322, the outer cannula may be 14 ga.and the inner cannula 16, 18, or 20 ga., for example. In any of theembodiments, the tubing 314 for secondary arterial branch 314 is ofsmaller diameter than the main arterial 318 and venous 314 branches. Thesecondary arterial branch 314 is used for drawing only enough blood toensure that the blood does not clot and to ensure that detection of airis established should the dual-lumen needle, which serves primarily thevenous return function, be accidentally withdrawn. By providing asmaller diameter tube, any air bubbles will travel along the tube morerapidly to an air detector as described below.

Referring now to FIG. 7A, a patient 308 has a two-needle accessemploying a needle set 301 as described with reference to FIG. 7D. Themain venous line 316 returns blood to the body and the main arterialline 318 draws blood and sends it through the Y junction 319, the commonarterial line 303 and into a treatment system 300. Within the treatmentsystem 300 is an air detector 302 and portion of the common arterialline 303 (or a further line connected thereto) which runs through theair detector 302. Any air drawn through the common arterial line 303 isdetected by the air detector 302. The air detector (or “bubbledetector”) is common on the arterial lines of blood treatment systems.The blood treatment system 300 may be one configured for dialysis,hemofiltration, apheresis, ultrafiltration, medication, plasmafiltration, plasma substitution, stem cell harvesting, or any kind ofblood treatment.

A two needle access is established as indicated at 310. A dual-lumenneedle 322 provides mainly venous flow through the inner cannula and viamain venous line 316. A small amount of arterial flow is drawn throughthe annular gap between the inner and outer cannulas in the dual-lumenneedle 322 and drawn into common arterial line 303 from arterial branchline 314 via Y junction 319. The lumen of the arterial branch line 314may be smaller than the other lines to allow air to be drawn quicklythrough it and to minimize the residence time of blood therein. As aresult, of the configuration, if the arterial access is ever lost due towithdrawal (accidental, for example), during pumping of blood, air willbe drawn into the common arterial line 303 due to exposure of theannular inlet of the dual-lumen needle 322 to ambient air. The air willbe detected by the air detector 302. In this way, but needles of thetwo-needle access 310 are protected against accidental withdrawal of aneedle.

Also, because the annular gap lumen of the dual-lumen needle 322 isprimarily used for the detection of withdrawal by inspiration of air,the annular gap may be minimized permitting the venous flow through thedual-lumen needle 322 to be high, as in a single lumen needle. Forexample, the inner cannula may be a 16 ga. cannula and the outer cannulamay be a 14 gage cannula leaving a large inner lumen available for highrate of venous flow. Another benefit is that the potential forshort-circuit (recirculating) flow between the inner and outer cannulasis minimized due to the large difference in flow rates.

FIG. 7B shows an alternative method and system for using two dual-lumenneedles 322 in a blood processing treatment. Here, the two dual-lumenneedles are used for both arterial and venous flow. The machine 300draws blood through a common arterial line 304 which is connected to theannular lumen of both dual-lumen needles 322 via a respective junction312 through arterial branch lines 332 and 334. The machine 300 returnsblood through a common venous line 305 which is connected to the innerlumen of both dual-lumen needles 322 via a respective junction 312through venous branch lines 336 and 338. As in the previous embodimentof FIG. 7A, the withdrawal of either needle will cause inspiration ofair into the common arterial line 304 and detection by the air detector302. A corresponding needle set for the FIG. 7B embodiment, similar toneedle set 301 (FIG. 7D), may be provided with instructions for use andpackaging.

FIG. 7C shows an alternative method and system for using a dual-lumenneedle in a blood processing treatment. The system is similar to that ofFIG. 7A, except that a separate module 358 is provided that may provideadditional functions. The module 358 may include a pump, for example, aperistaltic pump, to regulate the arterial flow through the arterialbranch line 314. The module 358 may further have a controller (orconnect to one in the treatment machine 300) which provides for variableflow rates of the arterial flow, for example, the flow may beintermittent according to a schedule. In this way, the secure insertionof the dual-lumen needle 322 can be confirmed at regular intervals, forexample, every 2 seconds or every 20 seconds or some other schedule. Themodule 358 may also incorporate an air detector 356 which may allow moreimmediate detection of a withdrawal of the dual-lumen needle 322. Acontroller on board the treatment machine 300 may instruct and power themodule 356 via a command interface 354 which may be wired or wireless.

A corresponding needle set for the FIG. 7C embodiment, similar to needleset 301 (FIG. 7D), may be provided with instructions for use andpackaging. The arterial branch line 314 may include pump segment forengagement with a peristaltic pump rotor. The pump segment may be aportion of tubing that is selected to interoperation with a pump rotor,for example, it may be of a material with different properties from thearterial branch line 314.

FIG. 8 shows a dual-lumen needle 400 having an alternative structure inwhich the outer cannula 404 is inserted directly in a junction component402 without an intermediate hub portion. The junction component 402 thussupports the outer cannula 404 directly. The outer cannula 404 may beobtained directly from a supplier or it may be obtained by removing itfrom a selected needle as obtained according to the method of FIG. 6.This feature of a direct-connected outer cannula may be used in any ofthe disclosed embodiments. As in some foregoing embodiments, a needle415 with an inner cannula 408 may be joined via its hub 410 to thejunction component 402 such that the lumen between the cannulas 404 and408 communicates with the port 410 through an internal space 412 definedby the junction component 402.

In any of the embodiments described herein, a sharp tipped inner cannulamay be used in conjunction with a blunt tip (buttonhole style) outercannula. Sharp tips may be difficult to insert or cause damage to thepatient's tissue due to the gap between the two cannulas. FIGS. 9Athrough 9B show features that may be used with sharp tip dual-lumenneedles to mitigate these problems in a dual-lumen needle with a sharpouter cannula and a sharp inner cannula. Referring to FIG. 9A, the inner420 and outer 432 cannulas of a dual-lumen needle 426 are sharpcannulas. A knife 424 may be attached to the inner cannula 420 or theouter cannula 432 or it may be self-supporting in the annular spacebetween. When the dual-lumen needle 426 is inserted, the knife 424 cutsthe tissue to prevent the tip of the outer cannula 432 from making aseparate opening in the tissue. A similar configuration with a differentmutual arrangement of the inner and outer cannulas is shown in FIG. 9B.The knife 428 performs the same function as knife 424.

FIG. 9C shows a dual-lumen needle 425 in end view spacers 434 (typ.)that may be used for separating an inner cannula 421 from an outercannula 435. The knife 424, 428 is indicated in the end view of FIG. 9C.Spacers may be provided and may be configured in any suitable manner.Spacers may be self-supporting or attached one or both of the inner andouter cannulas. Referring to FIG. 9D, a dual-lumen needle 440 is shownin end view. the inner cannula 44 may be positioned close to the wall ofthe outer cannula 442, for example by means of a spacer 444. The spacer444 may be a resilient material configured and arranged to act as a leafspring, thereby urging the inner cannula toward the wall of the outercannula. Such an alignment may permit the inner and outer cannulas towork effectively if both have cutting edges at their tips. The innercannula 44 may alternatively be attached to the inner lumen of the outercannula 442.

FIGS. 10A and 10B show a dual-lumen needle with an junction component514 that allows the inner cannula 506 to be retracted and extendedrelative to the outer cannula 512. The inner and outer cannulas 514 and512 are attached to respective hubs 516 and 518 and are assembled asneedles into the junction component 514 as discussed in the foregoingembodiments. The junction component 514 has a bellows 502 and acompression seal 520 that allow the hub 516 to be retracted forinsertion into a patient as shown at 501 in FIG. 10B and then extendedas shown at 500 in FIG. 10A. The seal 520 is optional but preferred whenthe fluid conveyed is blood or otherwise prone to clotting.

FIGS. 11A and 11B show a dual-lumen needle with an outer cannula thatcan be retracted and extended. A diaphragm 538 has two stable positions,shown respectively at 561 (outer cannula 532 retracted) and 562 (outercannula 532 extended). The diaphragm 538 may be provided with concentricaccordion folds that are compressed as the outer cannula 532 movesbetween the extended and retracted positions. The inner and outercannulas are supported in respective hubs 567 and 568 so that thecannulas are provided as full needle assemblies that are combined withthe junction component 536 to form a dual-lumen needle. The cannulas maybe sharp and in use the outer cannula 532 may be extended for insertioninto tissue and retracted during blood flow. In an alternativeembodiment, as in others, the outer cannula or the inner cannula alonemay be attached to the junction component and the other of the outer orinner cannula may be attached to the junction component as a needle witha hub. That is, in any of the embodiments, the outer cannula may bedirectly supported by the junction component rather than using the outercannula and hub as a complete needle. Also, in any of the embodiments,the inner cannula may be directly supported by the junction componentrather than using the inner cannula and hub as a complete needle.

It is, thus, apparent that there is provided, in accordance with thepresent disclosure fluid conveyance safety devices methods and systems.Many alternatives, modifications, and variations are enabled by thepresent disclosure. Features of the disclosed embodiments can becombined, rearranged, omitted, etc., within the scope of the disclosedsubject matter to produce additional embodiments. Furthermore, certainfeatures may sometimes be used to advantage without a corresponding useof other features. Accordingly, Applicants intend to embrace all suchalternatives, modifications, equivalents, and variations that are withinthe spirit and scope of the present claims.

What is claimed is:
 1. A method of providing vascular access, the methodcomprising: withdrawing blood from a patient through a first cannula;infusing blood into a patient through a second cannula; withdrawingblood through a secondary channel affixed to the second cannula suchthat a withdrawal of the second cannula from the patient is necessarilyattended by a disruption of fluid communication through the loss ofpatency; generating an alarm signal responsively to air being drawn intothe secondary channel.
 2. The method of claim 1, wherein the secondcannula is part of a dual lumen needle.
 3. The method of claim 1,wherein said generating an alarm signal includes passing blood resultingfrom said withdrawing blood through a secondary channel through an airdetector.
 4. The method of claim 1, further comprising infusing bloodthrough a second channel affixed to the first cannula.
 5. The method ofclaim 1, wherein the secondary channel and the second cannula arecoaxial cannulae.
 6. The method of claim 1, wherein the first cannula isa dual lumen cannula.
 7. The method of claim 1, wherein blood withdrawnthrough the first cannula and the secondary channel are combined into asingle flow and conveyed to an air detector.
 8. The method of claim 1,wherein blood withdrawn through the first cannula and the secondarychannel are pumped through a junction to form a single flow which isconveyed to an air detector.
 9. The method of claim 8, furthercomprising conveying the blood from the air detector to a bloodtreatment device.
 10. A vascular access device, comprising: a bloodcircuit having an arterial blood line and a venous blood line; thevenous blood line being connected to a first access needle and thearterial blood line being connected to a second access needle; thevenous blood line being connected to an access component affixed to thesecond access needle and configured such that when the second accessneedle is used to infuse blood into a patient, the access component ispositioned to withdraw blood and convey it into the venous line.
 11. Thedevice of claim 10, wherein second access needle a dual-lumen needle andthe access component is a lumen of the dual-lumen needle.
 12. The deviceof claim 10, wherein the second access needle includes a dual lumenneedle set and the access component is a lumen thereof.
 13. The deviceof claim 10, wherein the blood circuit is shaped to be engaged thevenous blood line to a predefined blood pump in a predefined orientationthat causes blood to be drawn from the first access needle when the pumpis operated.
 14. The device of claim 10, wherein the venous blood lineis connected to the access component through a tube junction.
 15. Avascular access device, comprising: a blood circuit having an arterialblood line and a venous blood line; the venous blood line beingconnected to a first access needle and the arterial blood line beingconnected to a second access needle; the venous blood line beingconnected to an access component affixed to the second access needle andconfigured such that when the second access needle is used to infuseblood into a patient, the access component is positioned to withdrawblood and convey it to an air detector.
 16. A needle set for a twoneedle vascular access, comprising: a dual-lumen needle with arterialand venous ports; a single lumen needle with an arterial port; and anarterial line with an arterial connector connected to the single lumenneedle arterial port and the dual-lumen needle arterial port; a venousline with a venous connector connected to the venous port.